1. Field of the Invention
The present invention relates to a light emitting diode (LED) and a flip-chip LED package, and particularly to an LED and a flip-chip LED package applicable to high current densities.
2. Description of Related Art
Electrical energy is one of the indispensable energy sources used nowadays. Many facilities, including lighting devices, home appliances, communication devices, transportation vehicles, or industrial equipment, cannot operate without electrical energy. The majority of current worldwide energy is generated by burning fuels such as petroleum or coal. However, the supply of petroleum or coal is not inexhaustible. The current rate of fuel usage will lead to an energy crisis. There is an urgent need to develop alternative energy sources to cope with the global energy crisis. Besides actively developing various kinds of renewable energy, people also need to use energy in an economical and efficient way for enhancing the utilization efficiency of energy.
Take lighting equipment as an example. Lighting equipment is essential to our daily lives. Lights with higher luminance and lower power consumption are developed along with the rapid development of modern technology. A light emitting diode (LED) is one of the most popular light sources available now. Compared with conventional light sources, an LED has the properties of compact volume, low power consumption, good light-emitting efficiency, long lifetime, fast response time, no heat radiation, and no pollutants such as mercury. Thus, the LED has been used widely in recent years. The conventional light sources have not been replaced by LEDs due to brightness problems. However, thanks to the continuous technical enhancements, the high brightness LED (the high-power LED) has been invented currently and is capable of replacing conventional light sources.
The conventional LED at least includes one substrate, an n-type semiconductor layer, a light emitting layer, a p-type semiconductor layer, an n-type electrode, and a p-type electrode. At least one trench is formed on the p-type semiconductor layer by etching and the trench is extended to the n-type semiconductor layer. The n-type electrode is disposed on the n-type semiconductor layer. The smaller the area of the trench is, the larger the light emitting area of the LED is. The heat accumulation problem occurs while the LED is worked at high current density and the contact area between the n-type electrode and the n-type semiconductor layer is quite small. On the other hand, the larger the area of the trench is, the smaller the light emitting area of the LED is. This leads to reduction in the light emitting efficiency of the LED.
In order to solve the above problems, there is a need to provide an LED and a flip-chip LED package in which the contact area between a first contact (n-type electrode) and a first-type-doped layer (n-type semiconductor layer) is controlled within a certain range. Thus, the LED can be worked at high current densities without heat accumulation. Moreover, the light emitting area of the LED is not reduced and the light emitting efficiency of the LED is not affected.